The invention relates to an electronically controlled self-timer for a camera, and more particularly, to an operating member associated therewith.
An electronically controlled self-timer which delays a shutter operation by a given time determined by an electrical delay circuit is simpler in construction and requires less space than a mechanical self-timer which involves a governor, and can be mounted on any location selected. With a camera which incorporates an electrical shutter, a mere addition of a delay circuit to the electrical shutter circuit permits it to be controlled by a self-timer switch, providing a very advantageous arrangement.
An electronically controlled self-timer is arranged such that its operation is enabled by a self-timer switch which is operated through a self-timer operating member, allowing a self-timer operation to be performed in response to the depression of a shutter button in the similar manner as it occurs in a mechanical self-timer. However, there is a difference between the electronically controlled self-timer and mechanical self-timer in respect of providing an indication of a self-timer operation. With a mechanical self-timer, an operating member returns to its initial position during the time the self-timer is in operation, thus giving an indication that the self-timer is in operation. However, with an electronic self-timer, the operating member maintains its position in which it holds the switch operative during the time the self-timer is in operation, and hence there must be some means which indicates the fact that the self-timer is in operation.
Another disadvantage of conventional electronically controlled self-timers is the fact that the operating member comprises a transfer knob of a very small size, which therefore may be left in its operative position by inadvertence, causing a next photographing operation to be initiated with the self-timer in operative condition.
A camera incorporating an electronically controlled self-timer having described disadvantages is illustrated in FIGS. 1 and 2. In these Figures, a camera body 1 includes a lens barrel 2, film winding knob 3, shutter button 4 and film rewind knob 5. An operating member of an electronically controlled self-timer is shown as a transfer knob 6 which is rotatably mounted on a shutter release rod on which the shutter button 4 is mounted. When it is turned 90.degree. clockwise as viewed in FIG. 2, to position 6A, the self-timer is rendered operative. In response thereto, a self-timer switch SW (see FIG. 3) is opened to connect a self-timer delay circuit 7 in circuit with the remainder of a shutter drive circuit.
Referring to FIG. 3, there is shown a circuit diagram of an electrical circuit which is used to drive a shutter. The circuit includes a power source 9 across which an electromagnet starting circuit 8 is connected in series with a main switch SW1. The circuit 8 has an output terminal which is connected with an electromagnet Mg which is adapted to drive a shutter. A self-timer delay circuit 7 is connected between the source 9 and the starting circuit 8 in series with a release switch SW2. The delay circuit 7 is normally short-circuited by the self-timer switch SW which is connected across its input and output terminals. Consequently, in the normal operation, the depression of shutter button 4 to close the release switch SW2 does not activate the circuit 7, only activating the starting circuit 8 to energize the electromagnet Mg to operate the shutter. However, when the transfer knob 6 is turned to position 6A, the switch SW becomes open, whereby the delay circuit 7 is enabled. As a result, the depression of the shutter button to close the release switch SW2 activates the delay circuit 7, allowing a self-timer operation to take place. After a given length of time delay, the starting circuit 8 is activated to energize the electromagnet Mg to operate the shutter.
As will be understood from the foregoing description, the transfer knob 6 which represents an operating member for the self-timer, is a small piece which is fitted over the shaft on which the shutter button 4 is mounted. Consequently, a user may inadvertently and often forget to return it to its original position after a self-timer operation has taken place, causing a failure in the next photographing operation.